Method and apparatus for providing multimedia broadcast and multicast service (mbms) in wireless communication system

ABSTRACT

A method for receiving a multimedia broadcast multicast service (MBMS) by a user equipment (UE) in a wireless communication system; the UE therefore; a method for transmitting an MBMS by a base station (BS) in a wireless communication system; and the BS therefore are discussed. The method for receiving an MBMS by a UE according to one embodiment includes transmitting one or more system information blocks (SIBs); receiving a first MBMS interest indication message indicating whether MBMS reception is prioritized above unicast reception, when a predetermined SIB related to MBMS service continuity is included in the one or more SIBs; and receiving a second MBMS interest indication message according to a change of priority between the MBMS reception and the unicast reception.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 14/540,812 filed on Nov. 13, 2014, which is a continuation ofU.S. patent application Ser. No. 14/480,320 filed on Sep. 8, 2014, whichis a continuation of U.S. patent application Ser. No. 13/808,872 filedon Jan. 7, 2013 (now U.S. Pat. No. 8,867,426, issued on Oct. 21, 2014),which is the National Phase of PCT/KR2012/006990 filed on Aug. 31, 2012,which claims priority under 35 U.S.C. 119(e) to U.S. ProvisionalApplication No. 61/530,375 filed on Sep. 1, 2011; U.S. ProvisionalApplication No. 61/537,027 filed on Sep. 20, 2011; U.S. ProvisionalApplication No. 61/541,101 filed on Sep. 30, 2011; U.S. ProvisionalApplication No. 61/555,487 filed on Nov. 4, 2011 and U.S. ProvisionalApplication No. 61/592,000 filed on Jan. 30, 2012. The entire contentsof all of the above applications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wireless communication system, andmore particularly to a method and apparatus for providing a multimediabroadcast and multicast service (MBMS).

2. Discussion of the Related Art

A multimedia broadcast and multicast service (MBMS) can allow a singletransmitter to simultaneously transmit the same multimedia content to aplurality of receivers using only one transmission action.

If the receiver desires to receive the MBMS, information indicating suchinterest can be transmitted to the transmitter, and the transmitter canenable the receiver to shift to a frequency at which the receiverreceives the MBMS, and at the same time can provide the MBMS.

SUMMARY OF THE INVENTION

One eNode B supporting the MBMS may coexist with another eNode B notsupporting the MBMS. If a user equipment (UE) transmits a messageindicating the MBMS interest to the eNode B not supporting the MBMS, afaulty operation of the corresponding eNode B may occur. However, sincethe existing wireless communication system has been defined only totransmit a message indicating the MBMS interest, there is a need todevelop and define a new method for preventing the occurrence of theabove-mentioned faulty operation.

An object of the present invention is to provide a method and apparatusfor enabling a user equipment (UE) to transmit an MBMS interestindication message under the control of an eNode B, and preventing notonly the faulty operation of the eNode B but also a waste of radioresources.

It will be appreciated by persons skilled in the art that the objectsthat can be achieved through the present invention are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present invention can achieve will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings.

The object of the present invention can be achieved by providing amethod for receiving a multimedia broadcast and multicast service (MBMS)by a user equipment (UE) in a wireless communication system, the methodincluding: obtaining a predetermined system information block (SIB) froma base station (BS); and transmitting an MBMS interest indicationmessage to the base station (BS) only when the predetermined systeminformation block (SIB) is obtained, wherein the predetermined systeminformation block (SIB) includes information related to MBMS continuity.

In another aspect of the present invention, a method for providing amultimedia broadcast and multicast service (MBMS) by a base station (BS)in a wireless communication system includes: broadcasting apredetermined system information block (SIB); and receiving an MBMSinterest indication message from the user equipment (UE), wherein theMBMS interest indication message is transmitted from the UE only whenthe UE obtains the predetermined system information block (SIB), and thepredetermined system information block (SIB) includes informationrelated to MBMS continuity.

In another aspect of the present invention, a user equipment (UE) forreceiving a multimedia broadcast and multicast service (MBMS) in awireless communication system includes: a reception module for receivinga downlink signal from a base station (BS); a transmission module fortransmitting an uplink signal to the base station (BS); and a processorfor controlling the user equipment (UE) including the reception moduleand the transmission module, wherein the processor enables the receptionmodule to obtain a predetermined system information block (SIB) from abase station (BS), and enables the transmission module to transmit anMBMS interest indication message to the base station (BS) only when thepredetermined system information block (SIB) is obtained, and thepredetermined system information block (SIB) includes informationrelated to MBMS continuity.

In another aspect of the present invention, a base station (BS) forproviding a multimedia broadcast and multicast service (MBMS) in awireless communication system includes a reception module for receivingan uplink signal from a user equipment (UE); a transmission module fortransmitting a downlink signal to the user equipment (UE); and aprocessor for controlling the base station (BS) including the receptionmodule and the transmission module, wherein the processor enables thetransmission module to broadcast a predetermined system informationblock (SIB), and enables the reception module to receive an MBMSinterest indication message from the user equipment (UE), wherein theMBMS interest indication message is transmitted from the UE only whenthe UE obtains the predetermined system information block (SIB), and thepredetermined system information block (SIB) includes informationrelated to MBMS continuity.

The following contents can be commonly applied to the above-mentionedembodiments.

The MBMS interest indication message may be used to indicate whether theUE is receiving the MBMS or is going to receive the MBMS.

The MBMS interest indication message may further include informationregarding an MBMS frequency at which the MBMS currently received by theUE or desired to be received by the UE is transmitted.

The MBMS interest indication message may further include MBMS priorityinformation.

The MBMS priority information may indicate whether the MBMS has priorityover a unicast service.

If the UE is handed over from a source cell to a target cell, the MBMSinterest indication message may be transmitted to the target cell aftercompletion of the handover.

The predetermined system information block (SIB) may be broadcast by thebase station (BS).

The UE may be in a radio resource control (RRC) connection state.

The UE may be configured to simultaneously receive the MBMS and aunicast service.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

Exemplary embodiments of the present invention have the followingeffects. The embodiments of the present invention can enable a userequipment (UE) to transmit an MBMS interest indication message under thecontrol of an eNode B, thereby preventing the faulty operation of theeNode B and a waste of radio resources.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved through the present invention are not limited towhat has been particularly described hereinabove and other advantages ofthe present invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

FIG. 1 is a diagram illustrating the architecture of a wirelesscommunication system.

FIG. 2 is a diagram illustrating a control plane of a radio protocol.

FIG. 3 is a diagram illustrating a user plane of a radio protocol.

FIG. 4 exemplarily shows the position of a PDCCH in one radio frame.

FIG. 5 is a diagram illustrating carrier aggregation (CA).

FIG. 6 is a diagram illustrating an MBMS channel structure.

FIG. 7 shows an exemplary scenario of an MBMS.

FIG. 8 is a flowchart illustrating a method for transmitting an MBMSinterest indication message according to one embodiment of the presentinvention.

FIG. 9 is a block diagram illustrating an eNB apparatus and a UEapparatus according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following embodiments are proposed by combining constituentcomponents and characteristics of the present invention according to apredetermined format. The individual constituent components orcharacteristics should be considered to optional factors on thecondition that there is no additional remark. If required, theindividual constituent components or characteristics may not be combinedwith other components or characteristics. Also, some constituentcomponents and/or characteristics may be combined to implement theembodiments of the present invention. The order of operations to bedisclosed in the embodiments of the present invention may be changed.Some components or characteristics of any embodiment may also beincluded in other embodiments, or may be replaced with those of theother embodiments as necessary.

The embodiments of the present invention are disclosed on the basis of adata communication relationship between a base station and a terminal.In this case, the base station is used as a terminal node of a networkvia which the base station can directly communicate with the terminal.Specific operations to be conducted by the base station in the presentinvention may also be conducted by an upper node of the base station asnecessary.

In other words, it will be obvious to those skilled in the art thatvarious operations for enabling the base station to communicate with theterminal in a network composed of several network nodes including thebase station will be conducted by the base station or other networknodes other than the base station. The term “Base Station (BS)” may bereplaced with a fixed station, Node-B, eNode-B (eNB), or an access pointas necessary. The term “relay” may be replaced with a Relay Node (RN) ora Relay Station (RS). The term “terminal” may also be replaced with theterms User Equipment (UE), Mobile Station (MS), Mobile SubscriberStation (MSS) or Subscriber Station (SS) as necessary.

It should be noted that specific terms disclosed in the presentinvention are proposed for convenience of description and betterunderstanding of the present invention, and the use of these specificterms may be changed to other formats within the technical scope orspirit of the present invention.

In some instances, well-known structures and devices are omitted inorder to avoid obscuring the concepts of the present invention and theimportant functions of the structures and devices are shown in blockdiagram form. The same reference numbers will be used throughout thedrawings to refer to the same or like parts.

Exemplary embodiments of the present invention are supported by standarddocuments disclosed for at least one of wireless access systemsincluding an Institute of Electrical and Electronics Engineers (IEEE)802 system, a 3^(rd) Generation Project Partnership (3GPP) system, a3GPP Long Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system,and a 3GPP2 system. In particular, the steps or parts, which are notdescribed to clearly reveal the technical idea of the present invention,in the embodiments of the present invention may be supported by theabove documents. All terminology used herein may be supported by atleast one of the above-mentioned documents.

The following embodiments of the present invention can be applied to avariety of wireless access technologies, for example, CDMA (CodeDivision Multiple Access), FDMA (Frequency Division Multiple Access),TDMA (Time Division Multiple Access), OFDMA (Orthogonal FrequencyDivision Multiple Access), SC-FDMA (Single Carrier Frequency DivisionMultiple Access), and the like. CDMA may be embodied through wireless(or radio) technology such as UTRA (Universal Terrestrial Radio Access)or CDMA2000. TDMA may be embodied through wireless (or radio) technologysuch as GSM (Global System for Mobile communications)/GPRS (GeneralPacket Radio Service)/EDGE (Enhanced Data Rates for GSM Evolution).OFDMA may be embodied through wireless (or radio) technology such asInstitute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi),IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (Evolved UTRA). UTRA is apart of UMTS (Universal Mobile Telecommunications System). 3GPP (3rdGeneration Partnership Project) LTE (long term evolution) is a part ofE-UMTS (Evolved UMTS), which uses E-UTRA. 3GPP LTE employs OFDMA indownlink and employs SC-FDMA in uplink. LTE-Advanced (LTE-A) is anevolved version of 3GPP LTE. WiMAX can be explained by an IEEE 802.16e(WirelessMAN-OFDMA Reference System) and an advanced IEEE 802.16m(WirelessMAN-OFDMA Advanced System). For clarity, the followingdescription focuses on 3GPP LTE and 3GPP LTE-A systems. However,technical features of the present invention are not limited thereto.

LTE System Structure

The architecture of an LTE system, which is an example of a wirelesscommunication system to which the present invention is applicable, isdescribed with reference to FIG. 1. The LTE system is a mobilecommunication system that has evolved from a UMTS system. FIG. 1 is aconceptual diagram illustrating an LTE system. Referring to FIG. 1, theLTE system can be generally classified into an Evolved UMTS (E-UTRAN)and an Evolved Packet Core (EPC). The E-UTRAN includes a UE and anEvolved Node-B (eNB). An interface between a UE and an eNB is referredto as a Uu interface, and an interface between eNBs is referred to as anX2 interface. The EPC may include a mobility management entity (MME) anda serving gateway (S-GW). An interface between an eNB and an MME isreferred to as an S1-MME interface, and an interface between an eNB andan S-GW is referred to as an S-U interface, and a generic term for thetwo interfaces may also be called an S1 interface.

A radio interface protocol is defined in the Uu interface which is aradio section, wherein the radio interface protocol is horizontallycomprised of a physical layer, a data link layer, a network layer, andvertically classified into a user plane for user data transmission and acontrol plane for signaling (control signal) transfer. Such a radiointerface protocol can be typically classified into L1 (first layer)including a PHY layer which is a physical layer, L2 (second layer)including MAC/RLC/PDCP layers, and L3 (third layer) including an RRClayer as illustrated in FIGS. 2 and 3, based on the three lower layersof an Open System Interconnection (OSI) reference model widely known inthe field of communication systems. Those layers exist as a pair in theUE and E-UTRAN, thereby performing data transmission of the Uuinterface.

Each layer of a radio protocol shown in FIGS. 2 and 3 is described.FIGS. 2 and 3 are views illustrating the control plane and user planearchitecture of the radio protocol, respectively.

A physical (PHY) layer serving as the first layer (L1) transmits aninformation transfer service to a higher layer over a physical channel.The physical (PHY) layer is connected to a Medium Access Control (MAC)layer serving as a higher layer over a transport channel. Through thetransport channel, data is transferred from the MAC layer to thephysical layer or is also transferred from the physical layer to the MAClayer. In this case, the transport channel is largely classified into adedicated transport channel and a common transport channel depending onwhether or not the channel is shared. In addition, data is transferredbetween different PHY layers (i.e., between a PHY layer of a transmitterand a PHY layer of a receiver) over a physical channel using radioresources.

A variety of layers exist in the second layer (L2). The MAC layer mapsvarious logical channels to various transport channels and performslogical channel multiplexing to map a plurality of logical channels toone transport channel. The MAC layer is connected to the RLC layer,which is a higher layer, through a logical channel. The logical channelis divided into a control channel for transmitting information on acontrol plane and a traffic channel for transmitting information on auser plane, according to the kind of transmitted information.

The radio link control (RLC) layer of the L2 layer segments andconcatenates data received from a higher layer, such that it controls adata size to suit radio data transmission at a lower layer. Forcontrolling data size, the RLC layer segments or concatenates datareceived from a higher layer. To support various QoS levels requisitefor various radio bearers (RBs), the RLC layer provides three RLC modes,Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode(AM). Specifically, an AM RLC performs a retransmission function usingan Automatic Repeat and Request (ARQ) function so as to implementreliable data transmission.

The packet data convergence protocol (PDCP) layer of the L2 layerenables efficient data transmission in IP packets such as IP version 4(IPv4) or IP version 6 (IPv6) packets on a radio link having arelatively narrow bandwidth. For this purpose, the PDCP layer performsheader compression to reduce the size of an IP packet header includingrelatively large and unnecessary control information. Since onlynecessary information is transmitted in the data header through headercompression, the transmission efficiency of the radio link is increased.In addition, in the LTE system, the PDCP layer performs a securityfunction, this security function is composed of a ciphering function(also called an encryption function) for preventing a third party fromeavesdropping on data and an integrity protection function forpreventing a third party from fraudulently handling data.

Referring to FIG. 2, the Radio Resource Control (RRC) layer located atthe top of the third layer (L3) is defined only in the control plane andis responsible for control of logical, transport, and physical channelsin association with configuration, reconfiguration and release of RadioBearers (RBs). The RB is a logical path that the first and second layers(L1 and L2) provide for data communication between the UE and the UTRAN.Generally, Radio Bearer (RB) configuration means that a radio protocollayer needed for providing a specific service, and channelcharacteristics are defined and detailed parameters and operationmethods thereof are configured. The Radio Bearer (RB) is classified intoa Signaling RB (SRB) and a Data RB (DRB). The SRB is used as atransmission passage of RRC messages in the control plane, and the DRBis used as a transmission passage of user data in the user plane.

In addition, a Non-Access Stratum (NAS) layer (not shown) located abovethe RRC layer is defined in a control plane between an MME and a UE. TheNAS layer mainly performs a function for supporting UE mobility and asession management function for establishing/maintaining IP connectionof a UE, and the like.

As described above, the MAC layer is connected to the RLC layer througha logical channel. The logical channel is generally classified into acontrol logical channel and a traffic logical channel. The controllogical channels provided by the MAC layer may include a BroadcastControl Channel (BCCH), a Paging Control Channel (PCCH), a CommonControl Channel (CCCH), a Dedicated Control Channel (DCCH), etc. Thetraffic logical channel may include a dedicated traffic channel (DTCH),etc.

In addition, the MAC layer is connected to the PHY layer through atransport channel. The downlink transport channel is associated withdata transmitted from a network to a UE. The downlink transport channelmay include a broadcast channel (BCH) for transmitting systeminformation, a paging channel (PCH) for transmitting a paging message, aDownlink-Shared Channel (DL-SCH) for transmitting a user traffic or acontrol message, a multicast channel (MCH) for transmitting a traffic orcontrol message of a downlink multicast or a broadcast service (i.e.,MBMS), and the like. The uplink transport channel is associated withdata transmitted from the UE to the network. The uplink transportchannel may include a Random Access Channel (RACH) for transmitting aninitial control message, a Uplink-Shared Channel (UL-SCH) fortransmitting a user traffic or a control message, etc.

The mapping relationship between the logical channel and the transportchannel is shown in Tables 1 and 2. Table 1 shows uplink channelmapping, and Table 2 shows downlink channel mapping.

TABLE 1 Transport channel Logical channel UL-SCH RACH CCCH X DCCH X DTCHX

TABLE 2 Transport channel Logical channel BCH PCH DL-SCH BCCH X X PCCH XCCCH X DCCH X DTCH X

In case of uplink, a transport channel (UL-SCH) is mapped to a logicalchannel (CCCH, DCCH, or DTCH) as shown in Table 1. In case of downlink,a transport channel (BCCH) is mapped to transport channels (BCH andDL-SCH) as shown in Table 2. In addition, a logical channel (PCCH) ismapped to a transport channel (PCH), and logical channels (CCCH, DCCH,DTCH) are mapped to the transport channel (DL-SCH).

The mapping relationship between the transport channel and the physicalchannel is shown in Tables 3 and 4. Table 3 shows uplink channelmapping, and Table 4 shows downlink channel mapping.

TABLE 3 TrCH Physical Channel UL-SCH PUSCH RACH PRACH

TABLE 4 TrCH Physical Channel DL-SCH PDSCH BCH PBCH PCH PDSCH MCH PMCH

In case of uplink, a transport channel (UL-SCH) is mapped to a PhysicalUplink Shared Channel (PUSCH) acting as a physical channel as shown inTable 3, and a transport channel (RACH) is mapped to a physical randomaccess channel (PRACH) acting as a physical channel. In case ofdownlink, as shown in Table 4, a transport channel (DL-SCH) is mapped toa physical downlink shared channel (PDSCH) acting as a physical channel,a transport channel (BCH) is mapped to a physical broadcast channel(PBCH) acting as a physical channel, a transport channel (PCH) is mappedto a physical channel (PDSCH), and a transport channel (MCH) is mappedto a physical multicast channel (PMCH) acting as a physical channel.

A physical channel may be located in a resource region defined not onlyby a predetermined unit of a time domain but also by a predeterminedunit of a frequency domain. The predetermined unit of the time domainmay correspond to a radio frame, a subframe, a slot or a symbol. Forexample, one radio frame includes 10 subframes, and one subframeincludes two slots, and one slot includes 7 symbols (e.g., 7 OFDMsymbols) in case of a normal cyclic prefix (CP). The frequency unit ofthe frequency domain may correspond to a subcarrier. The resource blockdefined in terms of a time-frequency domain is defined not only by aplurality of symbols of the time domain but also by a plurality ofsubcarriers of the frequency domain. For example, one resource block maycorrespond to a resource region defined by 7 OFDM symbols and 12subcarriers.

In addition, a physical downlink control channel (PDCCH) may be used totransmit downlink L1/L2 control information. PDCCH may be defined infirst N symbols (for example, 1≦N≦4) of a single subframe. FIG. 4exemplarily shows the position of a PDCCH in one radio frame. In FIG. 4,each of two slots contained in one subframe is 0.5 ms long, and aTransmission Time Interval (TTI) acting as a unit time of datatransmission is 1 ms long, and one radio frame may be 10 ms long.However, the frame structure shown in FIG. 4 is disclosed only forillustrative purposes, and the scope or spirit of the present inventionis not limited thereto.

Carrier Aggregation (CA)

Carrier aggregation (CA) technology supporting multiple carriers willhereinafter be described with reference to FIG. 5. Carrier aggregationcan support a system bandwidth up to a maximum of 100 MHz by grouping amaximum of 5 carriers (5 Component Carriers; 5 CCs) of a bandwidth unit(e.g., 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, or 20 MHz) defined in a legacywireless communication system (e.g., an LTE system). The bandwidth sizesof CCs used for carrier aggregation may be the same or different.Individual CCs have different frequency bands (or central frequencies).Although individual CCs used for carrier aggregation may be present oncontiguous frequency bands, other CCs present in discontinuous frequencybands may also be used for carrier aggregation. In the carrieraggregation technology, bandwidth sizes of UL and DL may besymmetrically or asymmetrically allocated. In the LTE-A system, theserving cell may be composed of a single downlink CC and a single uplinkCC, or may also be composed of a single downlink CC. However, the scopeor spirit of the present invention is not limited thereto, and one cellfor use in the evolved or other wireless communication system may beindependently configured only in uplink resources.

In case of carrier aggregation technology, one RRC connection is presentbetween a UE and an eNode B. A plurality of serving cells configured tobe used by the UE is classified into PCell and SCell. PCell maycorrespond to a serving cell for providing not only a security input(for example, E-UTAN Cell Global Identifier (ECGI), Physical CellIdentifier (PCI), Absolute Radio-Frequency Channel Number (ARFCN)) toperform establishment or re-establishment of RRC connection, but alsomobility information (for example, tracking area identity (TAI)) of theNAS layer. SCell may correspond to cells other than PCell.

In case of constructing a plurality of serving cells, SCell can be addedor released by the eNode B as necessary whereas PCell can always beused. After SCell has been added by the eNode B, the SCell can bedynamically used according to an activation or deactivation state.

Multimedia Broadcast and Multicast Service (MBMS)

MBMS is a point-to-multipoint (p-t-m) transmission method which enablesa plurality of UEs within the corresponding cell to simultaneouslyreceive the same packet using only one transmission action of the eNodeB within one cell. The LTE system based on the OFDMA transmission schemehas defined a multi-cell transmission scheme acting as a broadcasttransmission scheme in which a plurality of eNode Bs simultaneouslytransmits the same packet.

The LTE system defines an MBSFN (MBMS Single Frequency Network)synchronization area (or MBSFN synchronous region) in whichsynchronization transmission is available for the multi-celltransmission service. Synchronization transmission of cells contained inthe MBSFN synchronous region is possible, and inter-cell interferenceand diversity gain can be obtained through synchronization transmission.One cell belongs to one MBSFN synchronous region. A plurality of MBSFNregions (for example, 256 MBSFN regions) may be present in the MBSFNsynchronous region. The same radio resource region is allocated forMBSFN to cells contained in the MBSFN region, and the correspondingcells have broadcast channel information. A plurality of MCHs (forexample, a maximum of 16 MCHs) transmitted using the same coding methodmay be present in one MBSFN region. A service for providing a pluralityof broadcast contents (for example, a maximum of 30 broadcast contents)can be provided through one MCH.

FIG. 6 is a diagram illustrating an MBMS channel structure.

A logical channel (BCCH) can provide system information through varioustypes of system information blocks (SIBs). In association with MBMS, SIBType 2 (SIB2) may include configuration information regarding subframeallocated for MBSFN. In addition, SIB13 may include information (forexample, MCCH position information) necessary for obtaining MBMS controlinformation. While a master information block (MIB) from amonginformation transferred through a logical channel (BCCH) is provided tothe UE over a transport channel (BCG) and a physical channel (PBCH), SIB(for example, SIB2 or SIB13) can be provided to the UE over a transportchannel (DL-SCH) and a physical channel (PDSCH).

MCCH is a logical channel for transmitting MBMS control information (forexample, MBSFN area information, information regarding current ongoingMBMS sessions, etc.) and the like. MTCH is a logical channel fortransmitting MBMS user traffic data. MBMS control information maycorrespond to an MBMS-related RRC message. Each MBSFN region fortransmitting the same MBMS information/traffic includes one MCCHchannel. If one cell provides a plurality of MBSFN regions, the UE mayalso receive a plurality of MCCHs.

A logical channel (MCCH) and/or another logical channel (MTCH) may bemapped to a transport channel (MCH). MCH is based on thepoint-to-multipoint (p-t-m) transmission scheme, is broadcast within acell, and is used as a transport channel of the MBSFN subframe.Allocation of a subframe used for MBSFN may be semi-statically achievedin MBMS Coordination Entity (MCE). A transport channel (MCH) may bemapped to a physical channel (PMCH).

Assuming that the new MBMS is added, MBMS-Radio Network TemporaryIdentifier (M-RNTI) may be used by PDCCH so as to inform an idle-stateUE of new MBMS addition. For example, if an MBMS-related RRC message ischanged in a specific MCCH channel, an indicator indicating a specificMCCH and an M-RNTI can be transmitted through a PDCCH. The UE supportingthe MBMS receives an M-RNTI indicator and an MCCH indicator through thePDCCH, such that it can recognize the change of MBMS-related RRC messagein a specific MCCH, and can receive the specific MCCH. The RRC messageof MCCH can be changed every change period, and can repeatedly broadcastevery repetition period (RP).

Table 5 shows detailed description of MBMS-related channels from amongchannels shown in FIG. 6.

TABLE 5 Logical Channel BCCH SIB2: MCH subframe allocation informationSIB13: MCCH position information, etc. MTCH Data traffic information istransmitted to UE. MCCH MBSFN region information is transmitted everyMCCH RP. MTCH channel information (information of activated service) istransmitted. Transport MCH MCCH and MTCH transmission. Channel P-t-Mtransmission. Cell broadcast Physical Channel PMCH MCH is transmitted inMBSFN subframe PDCCH Service start indication (M-RNTI)

In addition, the UE may receive a dedicated service during the MBMSreception. For example, a certain user can view a TV program using hisor her smartphone, and at the same time can chat with other usersthrough instant messaging (IM) such as MSN or Skype using thesmartphone. In this case, TV viewing may correspond to an MBMS thatenables a plurality of UEs can simultaneously receive data, and the IMservice may correspond to a dedicated service separately provided toeach UE (here, the MBMS may correspond to a multicast/broadcast service,and the dedicated service may correspond to a unicast service). The MBMSis provided through an MTCH, and the dedicated service is providedthrough a dedicated bearer such as DCCH or DTCH. In this case, thebearer may indicate a logical/virtual connection for providing a servicehaving a predetermined quality (QoS), and the dedicated bearer mayindicate a bearer for a dedicated service for each UE.

It is assumed that a certain eNode B provides the MBMS and the dedicatedservice. It is also assumed that the eNode B can simultaneously use aplurality of frequencies within one region. Here, the frequency may be afrequency (i.e., MBMS frequency) corresponding to a unit used for MBMS.In order to efficiently utilize radio resources, the eNode B can providethe MBMS at only one frequency selected from among a plurality offrequencies, and can provide each UE with a dedicated bearer at allfrequencies. That is, both the MBMS and the dedicated service can beprovided at a frequency selected for MBMS.

If the UE having received the service using the dedicated bearer at afrequency not providing the MBMS desires to receive the MBMS, the UEneeds to be handed over to a frequency providing the MBMS. For thispurpose, the UE can transmit an MBMS interest indication message to theeNode B. In other words, if the UE desires to receive the MBMS, the UEtransmits the MBMS interest indication message to the eNode B. If theeNode B supporting the MBMS receives the MBMS interest indicationmessage, this means that the UE desires to receive the MBMS, so that theUE can be shifted to or handed over to a frequency providing the MBMS.

In this case, the MBMS interest indication message indicates that the UEdesires to receive the MBMS. In addition, the MBMS interest indicationmessage may include information regarding a target frequency desired bythe UE. That is, the MBMS interest indication message is used toindicate that the UE is receiving the MBMS or the UE is going to receive(or is interested to receive) the MBMS. The MBMS interest indicationmessage may further include MBMS frequency information used fortransmission of the MBMS that is currently received by the UE or isgoing to be received by the UE.

Improved MBMS Operation Scheme

The user equipment (UE) for use in a mobile communication system hasmobility. That is, the UE does not stay in one place, and the UEposition may be changed according to time. Although the cell includingthe UE is changed due to the UE mobility, it is necessary to provide aseamless MBMS. Alternatively, although a frequency used by the UE ischanged when the UE stays in the same position, it is necessary toprovide a seamless MBMS. In various cases such as an exemplary case inwhich a frequency or cell used by the UE is changed, if the UE cancontinuously receive the MBMS, this situation means the MBMS continuityfunction.

If the MBMS is supported in all regions and all frequencies, it is notdifficult to provide the MBMS continuity. However, the MBMS may not beprovided in all regions or all frequencies. For example, the MBMS maynot be provided in a specific region, or a specific service from among avariety of MBMSs may not be provided at a frequency.

FIG. 7 shows an exemplary scenario of an MBMS. In the example of FIG. 7,the MBMS may not be provided to a frequency band of a frequency (f0),and the MBMS may not be provided to the frequency band of (f1) (here, f0and f1 may be distinguished from each other in terms of MBMS provision).That is, MBMS may be available to the cell A0 whereas MBMS may not beavailable to the cell A1. In this case, Cell A0 and Cell A1 maycorrespond to different eNode Bs, or may correspond to a plurality ofcells of a single eNode B in terms of carrier aggregation. In contrast,whereas the MBMS is provided in the f0 frequency band of the B region,the f1 frequency band may not provide the MBMS. Cell B0 and Cell B1 maybelong to different eNode Bs, or may correspond to a plurality of cellsin terms of carrier aggregation. In this case, an MBMS available orunavailable state in a specific cell may indicate an available orunavailable state of the MBMS, or may indicate that a specific MBMS (forexample, some TV broadcast programs from among a plurality of TVbroadcast programs) is available or unavailable.

In FIG. 7, it is assumed that a certain UE receives the MBMS within thecell A1. Provided that the corresponding UE maintains the same frequencyand at the same time moves from the A region to B region, or providedthat the frequency is changed from f1 to f0 although the geographiclocation is not changed, the UE belongs to a cell for providing no MBMS.In this case, it is impossible to provide the UE with the MBMScontinuity.

Provided that the UE contained in Cell A0 or Cell B1 desires to receivethe MBMS as shown in FIG. 7, the UE transmits the MBMS interestindication message to the eNode B. From the viewpoint of the UE,although the eNode B supporting no MBMS receives the MBMS interestindication message from the UE, it is impossible for the eNode B toprovide the MBMS. In this case, if the UE does not receive a response tothe MBMS interest indication message from the eNode B, it is difficultto recognize how to operate the UE. In some cases, a waste of radioresources may occur in the UE or the faulty operation may also occur inthe UE. Although an eNode B supporting no MBMS receives the MBMSinterest indication message, it is difficult to recognize how to operatethe eNode B, and the faulty operation and a waste of radio resources mayoccur in the eNode B. Therefore, there is a need for the UE and theeNode B to correctly and efficiently perform the transmission/receptionoperations of the MBMS interest indication message.

Embodiment 1

A first embodiment (Embodiment 1) relates to a method for enabling theUE to transmit the MBMS interest indication message to the eNode B. Inmore detail, the eNode B can provide information as to whether the UEtransmits the MBMS interest indication message to the UE.

For example, information as to the MBMS interest indication transmissionis allowed can be defined as the following various information types (i)to (v). Information (i) directly or indirectly indicates whethertransmission of the MBMS interest indication message of the UE isallowed. Information (ii) indicates a specific time or condition inwhich transmission of the MBMS interest indication message of the UE isallowed. Information (iii) indicates whether transmission of the MBMSinterest indication message of the UE is requested. Information (iv)indicates whether the eNode B supports the function related totransmission of the MBMS interest indication message. Information (v)indicates whether the eNode B supports the MBMS continuity function. Theabove-mentioned exemplary information i) to v) may be used independentlyof each other, or one or more information pieces may be simultaneouslyused.

Therefore, if transmission of the MBMS interest indication message isallowed, if a specific condition is satisfied, if the eNode B requeststransmission of the MBMS interest indication message, if the eNode Bsupports the MBMS interest indication associated function, and/or if theeNode B supports the MBMS continuity function, the UE can transmit theMBMS interest indication message to the eNode B.

In addition, although the UE desires to transmit the MBMS interestindication message to the network, if transmission of the MBMS interestindication message is not allowed, if a specific condition is notsatisfied, if the eNode B does not request transmission of the MBMSinterest indication message, if the eNode B does not support the MBMSinterest indication associated function, and/or if the eNode B does notsupport the MBMS continuity function, the UE may not transmit the MBMSinterest indication message to the eNode B.

In more detail, information indicating whether MBMS interest indicationtransmission is allowed can be provided to the UE through a systeminformation block (SIB). That is, if the serving eNode B (or the servingcell) provides a predetermined SIB and the UE obtains the predeterminedSIB of the current serving cell, the UE can indicate its own MBMSinterest message.

The predetermined SIB may be defined as a new type SIB not defined yet,and may be referred to as SIB15 as an example. The new type SIB mayinclude information related to MBMS reception considering UE mobility.The MBMS reception considering the UE mobility may indicate supportingthe MBMS continuity to the UE that moves in the same MBSFN region. Thescope of the present invention includes various schemes indicatingwhether transmission of the MBMS interest indication message for the UEis allowed through the new type SIB. For example, the scope of thepresent invention may include a scheme for explicitly includinginformation indicating whether MBMS interest indication transmission isallowed in the new type SIB, and a scheme for allowing transmission ofthe MBMS interest indication message if the UE obtains the new type SIB.

In addition, information as to whether transmission of the MBMS interestindication message is allowed may be provided to the UE using the RRCmessage. That is, only when the MBMS interest indication transmission isallowed through the RRC message is indicated/established, the UE canindicate its own MBMS interest.

In addition, the eNode B can transmit a variety of information to the UEusing the RRC message and/or the SIB, for example, information as towhether the eNode B supports the function related to the MBMS interestindication transmission of the UE, and information as to whether theeNode B supports the function related to MBMS continuity.

The above-mentioned principles of the present invention can also be usedas a method for providing specific information as to whether an eNode Bof a target cell allows transmission of the MBMS interest indicationmessage of the UE even when the UE is handed over from a current servingcell (i.e., a source cell) to the target cell.

For example, if the UE is handed over from a currently connected eNode B(i.e., a source cell) to a new cell (i.e., a target cell), it isimpossible for the UE to recognize whether transmission of the MBMSinterest indication message is allowed in the new cell, such that it ispossible to receive and read SIB of the new cell before updating theMBMS interest. For example, in the same manner as in the case in whichthe UE is handed over from Cell A0 to Cell B0 of FIG. 7, if the sourcecell does not provide the new type SIB and the target cell provides thenew type SIB (i.e., information as to whether transmission of the MBMSinterest indication message is allowed), the UE can indicate its ownMBMS interest after performing a handover. That is, if the new type SIB(i.e., SIB related to allowance or rejection of MBMS interest indicationtransmission) is contained in an SIB provided by a new cell aftercompletion of a UE handover, and if the UE obtains the correspondingSIB, the UE can indicate its own MBMS interest in a new cell.

In addition, the above-mentioned examples of the present invention canalso be equally applied to another case in which the target cellprovides specific information indicating whether the MBMS interestindication transmission is allowed through the RRC message.

In addition, if the UE receives a handover (HO command from the sourcecell, and if the HO command includes indication information forcommanding the UE to transmit the MBMS interest indication message in anew cell, the UE enters a new target cell instead of the source cell andthen transmits the MBMS interest indication message to the target cell.

Embodiment 2

In accordance with a second embodiment (Embodiment 2), the eNode B canrequest information related to transmission of the UE's MBMS interestindication message from the UE, and/or the UE can provide the aboveinformation to the eNode B.

For example, information related to the MBMS interest indicationtransmission may be information of MBMS-related priority. The eNode Bcan transmit a message (for example, RRC message) requesting the MBMSpriority information to the UE. In this case, information as to whatinformation to be obtained from the UE by the eNode B is can becontained in the request message. In addition, the UE may transmit amessage (for example, the MBMS interest indication message or other RRCmessage) including MBMS priority information to the eNode B. Theabove-mentioned message may be a response to the request message of theeNode B, or may be transmitted from the UE without receiving a requestfrom the eNode B.

In this case, the MBMS priority information may include the followingvarious types of information (i) to (vi). Information (i) indicateswhether the UE desires to receive the MBMS. Information (ii) indicateswhether the UE receives the current MBMS. Information (iii) indicateswhether the UE has priority over the MBMS or has priority over theunicast service. Information (iv) indicates whether the UE willaccommodate a Quality of Service (QoS) lower than a QoS established in aunicast service (or a dedicated bearer for transmitting data of theunicast server). Information (v) indicates which of a Guaranteed BitRate (GBR) service and an MBMS is more preferred by the UE. Information(vi) indicates whether the UE wants to continuously receive a seamlessunicast service. The above-mentioned information (i) to (vi) may be usedindependently of each other, or one or more information may besimultaneously used.

For example, the UE may transmit the MBMS interest indication messageincluding information regarding one or more MBMS frequencies at which anMBMS session currently received by the UE or desired to be received bythe UE is transmitted, to the eNode B. The MBMS interest indicationmessage may include specific information indicating whether reception atthe MBMS frequency indicated by the UE has priority over reception atthe unicast bearer or vice versa (that is, reception at the unicastbearer has priority over reception at the MBMS frequency indicated bythe UE).

Embodiment 3

A third embodiment (Embodiment 3) relates to a method for includinginformation regarding the neighbor cell in the MBMS interest indicationmessage.

As described above, the MBMS interest indication message may includeinformation regarding the MBMS frequency at which the MBMS session beingreceived by the UE is transmitted, or may include information regardingthe MBMS frequency at which the MBMS session desired to be received bythe UE is transmitted.

If the UE having an RRC_connected state and an MBMS capability transmitsthe above MBMS interest indication message, the above message maycorrespond to a message for preventing the UE from moving to anotherMBMS frequency from the viewpoint of a cell providing the MBMS, and theabove message may correspond to a message for requesting shifting toanother frequency providing the MBMS from the viewpoint of the cellproviding no MBMS. In the latter case, if shifting to another frequencyrequested by the UE is allowed, the overall system throughput may bedeteriorated. For example, if cells on the frequency shifting-requestedby the UE do not satisfy a predetermined quality, the UE shifted to thecorresponding frequency does not correctly communicate with the eNode B,so that poor connection between the UE and the eNode B may occur or aradio link failure may also occur.

In the third embodiment (Embodiment 3), in order to prevent theabove-mentioned problems, when transmitting the MBMS interest indicationmessage to the eNode B, the UE may further transmit the measurementresult of neighbor cells. In this case, the measurement result mayinclude information such as the signal strength of the correspondingcell. The measurement result may be contained in the MBMS interestindication message. Although the measurement result is transmittedthrough a separate message, the measurement result may be transmitted inconnection with (or simultaneously with) the MBMS interest indicationmessage. For example, the UE can transmit only the measurement result ofcells present at a desired MBMS frequency to the eNode B, instead ofreporting the measurement result of all the neighbor cells.

As an additional example, when the UE transmits the MBMS interestindication message including MBMS frequency information to the eNode B,the UE may further transmit information regarding a cell satisfying apredetermined reference from among a plurality of cells present at theMBMS frequency. In this case, the predetermined reference may beestablished by the eNode B, or may correspond to a minimum qualityreference as an example. Information regarding cell(s) satisfying thepredetermined reference may be contained in the MBMS interest indicationmessage, may be transmitted through a separate message, and/or may betransmitted in relation with (simultaneously with) the MBMS interestindication message.

In addition, information indicating the presence or absence of the cellsatisfying the predetermined reference may be used as a condition fortransmitting the MBMS interest indication message. For example, if theUE takes interest in reception of the MBMS provided at a secondfrequency different from the first frequency used as the currentfrequency, the UE measures the second frequency. Only when the cellsatisfying a predetermined quality reference at the second frequency isfound, the UE can transmit the MBMS interest indication message to theeNode B.

FIG. 8 is a flowchart illustrating a method for transmitting an MBMSinterest indication message according to one embodiment of the presentinvention.

Referring to FIG. 8, the eNode B can transmit information indicatingwhether transmission of the MBMS interest indication message is allowedto the UE in step S810. For example, information indicating whether theMBMS interest indication transmission is allowed may correspond to apredetermined system information block (SIB) broadcast to a plurality ofUEs contained in the cell. The predetermined SIB may include informationrelated to the MBMS continuity.

In step S820, the UE can obtain information indicating whether MBMSinterest indication transmission is allowed. For example, if thepredetermined SIB is broadcast by the eNode B, the UE can obtain thepredetermined SIB over a PDSCH.

The UE can transmit the MBMS interest indication message to the eNode Bin step S830. Information indicating whether the step S830 is performedcan be determined according to whether the UE has obtained allowanceinformation of the MBMS interest indication transmission in step S820.That is, only when the UE has obtained the MBMS interest indicationtransmission allowance information (for example, the predetermined SIB),the UE can transmit the MBMS interest indication message to the eNode B.

In association with the above-mentioned operation for transmitting andreceiving the MBMS interest indication message, the contents describedin the above-mentioned embodiments may be used independently of eachother or two or more embodiments may be simultaneously applied, and thesame parts may be omitted herein for convenience and clarity ofdescription.

FIG. 9 is a block diagram illustrating an eNB apparatus 910 and a UEapparatus 920 according to embodiments of the present invention.

Referring to FIG. 9, an eNB apparatus 910 may include a reception (Rx)module 911, a transmission (Tx) module 912, a processor 913, a memory914, and a plurality of antennas 915. The plurality of antennas 915 maybe contained in the eNB apparatus supporting MIMO transmission andreception. The reception (Rx) module 911 may receive a variety ofsignals, data and information on uplink starting from the UE. Thetransmission (Tx) module 912 may transmit a variety of signals, data andinformation on downlink for the UE. The processor 913 may provideoverall control to the eNB apparatus 910.

The eNB apparatus 910 according to one embodiment of the presentinvention is configured to provide the MBMS.

The processor 913 of the eNB apparatus 910 is configured to transmitinformation indicating allowance or rejection of MBMS interestindication transmission to the UE 920 through the transmission (Tx)module 912. For example, the information indicating allowance orrejection of the MBMS interest indication transmission may correspond toa predetermined SIB broadcast to a plurality of UEs contained in thecell. The predetermined SIB may include information related to the MBMScontinuity.

In addition, the processor 913 is configured to receive the MBMSinterest indication message from the UE through the reception (Rx)module 911. In this case, the MBMS interest indication message can betransmitted from the UE 920 only when the UE 920 obtains the MBMSinterest indication transmission allowance information.

The processor 913 of the eNB apparatus 910 processes informationreceived at the eNB apparatus 910 and transmission information. Thememory 914 may store the processed information for a predetermined time.The memory 914 may be replaced with a component such as a buffer (notshown).

Referring to FIG. 9, a UE apparatus 920 may include a reception (Rx)module 921, a transmission (Tx) module 922, a processor 923, a memory924, and a plurality of antennas 925. The plurality of antennas 925 maybe contained in the UE apparatus supporting MIMO transmission andreception. The reception (Rx) module 921 may receive a variety ofsignals, data and information on downlink starting from the eNB. Thetransmission (Tx) module 922 may transmit a variety of signals, data andinformation on uplink for the eNB. The processor 923 may provide overallcontrol to the UE apparatus 920.

The UE apparatus 920 according to one embodiment of the presentinvention is configured to receive the MBMS.

The processor 923 of the UE apparatus 920 is configured to obtaininformation indicating allowance or rejection of MBMS interestindication transmission from the eNode B 910 through the reception (Rx)module 921. For example, the information indicating allowance orrejection of the MBMS interest indication transmission may correspond toa predetermined SIB broadcast to a plurality of UEs contained in thecell. The predetermined SIB may include information related to the MBMScontinuity.

In addition, the processor 923 is configured to obtain allowanceinformation of MBMS interest indication transmission. In this case, theMBMS interest indication message can be transmitted to the eNode B 910through the transmission (Tx) module 922 only when the processor 923obtains the MBMS interest indication transmission allowance information.

The processor 923 of the UE apparatus 920 processes information receivedat the UE apparatus 920 and transmission information. The memory 924 maystore the processed information for a predetermined time. The memory 924may be replaced with a component such as a buffer (not shown).

The specific configurations of the above eNB and UE apparatuses may beimplemented such that the various embodiments of the present inventionare performed independently or two or more embodiments of the presentinvention are performed simultaneously. Redundant matters will not bedescribed herein for clarity.

The eNB apparatus 910 shown in FIG. 9 may also be applied to differenttypes of entities providing the MBMS, and the UE apparatus 920 shown inFIG. 9 may also be applied to different types of entities providing theMBMS.

The above-described embodiments of the present invention can beimplemented by a variety of means, for example, hardware, firmware,software, or a combination of them.

In the case of implementing the present invention by hardware, thepresent invention can be implemented with application specificintegrated circuits (ASICs), Digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), a processor, a controller, amicrocontroller, a microprocessor, etc.

If operations or functions of the present invention are implemented byfirmware or software, the present invention can be implemented in theform of a variety of formats, for example, modules, procedures,functions, etc. The software codes may be stored in a memory unit sothat it can be driven by a processor. The memory unit is located insideor outside of the processor, so that it can communicate with theaforementioned processor via a variety of well-known parts.

The detailed description of the exemplary embodiments of the presentinvention has been given to enable those skilled in the art to implementand practice the invention. Although the invention has been describedwith reference to the exemplary embodiments, those skilled in the artwill appreciate that various modifications and variations can be made inthe present invention without departing from the spirit or scope of theinvention described in the appended claims. For example, those skilledin the art may use each construction described in the above embodimentsin combination with each other. Accordingly, the invention should not belimited to the specific embodiments described herein, but should beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above exemplary embodiments are therefore to beconstrued in all aspects as illustrative and not restrictive. The scopeof the invention should be determined by the appended claims and theirlegal equivalents, not by the above description, and all changes comingwithin the meaning and equivalency range of the appended claims areintended to be embraced therein. Also, it will be obvious to thoseskilled in the art that claims that are not explicitly cited in theappended claims may be presented in combination as an exemplaryembodiment of the present invention or included as a new claim bysubsequent amendment after the application is filed.

The embodiments of the present invention are applicable not only to theMBMS but also to a variety of mobile communication systems supportingother similar services. It will be apparent to those skilled in the artthat various modifications and variations can be made in the presentinvention without departing from the spirit or scope of the invention.Thus, it is intended that the present invention cover the modificationsand variations of this invention provided they come within the scope ofthe appended claims and their equivalents.

What is claimed is:
 1. A method for receiving a multimedia broadcastmulticast service (MBMS) by a user equipment (UE) in a wirelesscommunication system, the method comprising: acquiring one or moresystem information blocks (SIBs) from a base station; transmitting afirst MBMS interest indication message indicating whether MBMS receptionis prioritized above unicast reception, when a predetermined SIB relatedto MBMS service continuity is included in the one or more SIBs; andtransmitting a second MBMS interest indication message according to achange of priority between the MBMS reception and the unicast reception.2. The method of claim 1, wherein the unicast reception is released,when the MBMS reception has been prioritized and the unicast receptioncannot be supported because of congestion on an MBMS carrier.
 3. Themethod of claim 1, wherein the transmitting of the first MBMS interestindication message or the second MBMS interest indication message isallowed only when the predetermined SIB is acquired.
 4. The method ofclaim 1, wherein the UE is configured to simultaneously receive the MBMSand unicast service.
 5. The method of claim 1, wherein MBMS priorityinformation which prioritizes the MBMS reception above the unicastreception is included in either the first MBMS interest indicationmessage or the second MBMS interest indication message.
 6. The method ofclaim 1, wherein the first MBMS interest indication message includesinformation about whether the UE is receiving or interested to receivethe MBMS via an MBMS single frequency network (MBSFN).
 7. A method fortransmitting a multimedia broadcast multicast service (MBMS) by a basestation (BS) in a wireless communication system, the method comprising:transmitting one or more system information blocks (SIBs); receiving afirst MBMS interest indication message indicating whether MBMS receptionis prioritized above unicast reception, when a predetermined SIB relatedto MBMS service continuity is included in the one or more SIBs; andreceiving a second MBMS interest indication message according to achange of priority between the MBMS reception and the unicast reception.8. The method of claim 7, wherein the unicast reception is released,when the MBMS reception has been prioritized and the unicast receptioncannot be supported because of congestion on an MBMS carrier.
 9. Themethod of claim 7, wherein the first MBMS interest indication message orthe second MBMS interest indication message is received only when thepredetermined SIB is transmitted.
 10. The method of claim 7, wherein theBS is configured to simultaneously transmit the MBMS and unicastservice.
 11. The method of claim 7, wherein MBMS priority informationwhich prioritizes the MBMS reception above the unicast reception isincluded in either the first MBMS interest indication message or thesecond MBMS interest indication message.
 12. The method of claim 7,wherein the first MBMS interest indication message includes informationabout whether a user equipment (UE) is receiving or interested toreceive the MBMS via an MBMS single frequency network (MBSFN).
 13. Auser equipment (UE) for receiving a multimedia broadcast multicastservice (MBMS), the UE comprising: a processor configured to acquire oneor more system information blocks (SIBs) from a base station; and atransmitter configured to: transmit a first MBMS interest indicationmessage indicating whether MBMS reception is prioritized above unicastreception, when a predetermined SIB related to MBMS service continuityis included in the one or more SIBs, and transmit a second MBMS interestindication message according to a change of priority between the MBMSreception and the unicast reception.
 14. The UE of claim 13, wherein theunicast reception is released, when the MBMS reception has beenprioritized and the unicast reception cannot be supported because ofcongestion on an MBMS carrier.
 15. The UE of claim 13, wherein the MBMSinterest indication message includes information about whether a userequipment (UE) is receiving or interested to receive an MBMS via an MBMSsingle frequency network (MBSFN).
 16. The UE of claim 13, wherein MBMSpriority information which prioritizes the MBMS reception above theunicast reception is included in either the first MBMS interestindication message or the second MBMS interest indication message.
 17. Abase station (BS) for transmitting a multimedia broadcast multicastservice (MBMS), the BS comprising: a transmitter configured to transmitone or more system information blocks (SIBs); and a receiver configuredto: receive a first MBMS interest indication message indicating whetherMBMS reception is prioritized above unicast reception, when apredetermined SIB related to MBMS service continuity is included in theone or more SIBs, and receive a second MBMS interest indication messageaccording to a change of priority between the MBMS reception and theunicast reception.
 18. The BS of claim 17, wherein the unicast receptionis released, when the MBMS reception has been prioritized and theunicast reception cannot be supported because of congestion on an MBMScarrier.
 19. The BS of claim 17, wherein the MBMS interest indicationmessage includes information about whether a user equipment (UE) isreceiving or interested to receive the MBMS via an MBMS single frequencynetwork (MBSFN).
 20. The BS of claim 17, wherein MBMS priorityinformation which prioritizes the MBMS reception above the unicastreception is included in either the first MBMS interest indicationmessage or the second MBMS interest indication message.